1. The Field of the Invention
The present invention is directed toward a method and apparatus for applying heat to a transdermal drug delivery system. More specifically, the invention is a securable compartment with a corresponding freely transferrable heating element for use with dermal drug delivery patches.
2. The Background Art
It has been discovered recently that the transdermal delivery of certain drugs can be facilitated by the application of heat. Controlled heat is provided to transdermal drug delivery patches using various techniques and apparatus such as heat generating patches. The heat generating patches sometimes utilize heat generated from chemical reactions, such as an oxidation reaction, or may utilize heat generated by an electrical current or some other method. One of the disadvantages of prior art heating apparatus for the transdermal drug patches is that the heating element must be secured to the transdermal patch without compromising the transdermal drug patch""s attachment to the user""s skin. In other words, sometimes when a user attempts to attach, replace, or adjust a heating patch or similar device, the drug delivery patch can become dislodged or otherwise made less secure. If the drug patch is not properly situated, the drug delivery system may be compromised. It is important in transdermal drug delivery that the skin be in contact with the formulation of the drug delivery patch to achieve efficient drug transfer.
Several methods for attaching or integrating a controlled heating element have been taught in the prior art. For example, wraps, adhesives, and tapes have all been suggested as potential ways for attaching a heating element to a patient""s body or to a transdermal drug patch. Attempting to attach a heating element to a transdermal drug patch these ways has several disadvantages.
When a prior art adhesive technique is used to apply the heating element to the drug patch, the process of applying the heating element to the patch may cause the drug delivery patch to become less secure. To apply the heating element using adhesive, the areas of the heating element that contain the adhesive must be pressed firmly against the heating patch to secure the heating element to the patch. During this process, the drug delivery system may be unintentionally compromised.
In the event that the user needs to remove, replace or change the heating element, any attempts to remove the heating element may cause the adhesive of the transdermal patch to be compromised, and thus to compromise the drug delivery. The continued removal and replacement of the heating element may cause the transdermal drug patch to lose enough adhesive that the drug patch does not properly contact the skin and thereby become less effective and less secure.
A significant problem with using prior art wraps to secure a heating element to a transdermal drug patch is the potential for the heating element and/or the drug patch to become dislodged. If the heating element is secured using a wrap or tie, as the heating element is being tied to or wrapped into the user or the drug patch on the user, the process of tying or wrapping the heating element can cause the drug patch to lose contact with the skin of the patient and thereby compromise the drug delivery.
Another disadvantage of prior art teachings is the inconvenience associated with trying to remove a heating element that is attached by a wrap. In order to change or remove the heating element, the user must attempt to unwrap the heating element from the transdermal patch without disturbing the transdermal patch. This can be particularly difficult if the user needs to make the change quickly or if the patch is located in a position that makes delicately removing and replacing the heating element wrap impractical. For example, if the heating element were secured to a patch by a wrap that went around a patient""s torso, frequent removal of the wrap could require substantial extra effort and work on the part of the patient and/or the user.
Another disadvantage of prior art teachings is the cost of integrating a heat element with a transdermal patch, particularly for heating elements that have limited uses and applications. If a patient requires a certain level of heating in one circumstance and a different level of heating in another, then the integrated patch must be removed and an entirely different patch with an appropriate heating level must be applied. Alternatives to this would require complex patch designs that attempt to control or modify the amount of heat generated by the heating element. Thus, using an integrated patch may increase manufacturing costs significantly. Moreover, modified and integrated designs may prove to be less reliable and may be prone to misuse.
Another disadvantage of the prior art is the potential for abuse where the heating element neither corresponds to a specific patch nor is integrated with a particular patch. If a heating patch can be freely used with any given transdermal device, there is a potential for the patch to be abused by a patient or misused by the user. For example, the patient may apply a heating element that induces an absorption rate that is too fast or delivers too much drug. Conversely, the user may apply a heating element that fails to supply sufficient heat for a particular treatment. Thus, where the patches do not correspond to the heating elements used with them, there is a potential for abuse or misuse.
In view of the foregoing, it is an object of at least one embodiment of the present invention to provide a securable heating element compartment with corresponding freely transferrable heating element.
It is another object of at least one embodiment of the present invention to provide a heating element advantageously secured to a transdermal drug patch.
It is another object of at least one embodiment of the present invention to provide a transdermal drug patch with a corresponding heating element pouch.
It is another object of at least one embodiment of the present invention to provide a heating element that is securely attached to but freely removable from a transdermal drug delivery patch.
It is another object of at least one embodiment of the present invention to provide a transdermal drug delivery patch and corresponding heating element that allows a heating element to be used to decrease the time necessary to reach steady state and that can be conveniently replaced with another heating element with different heating characteristics that provide different results.
It is another object of at least one embodiment of the present invention to provide a transdermal drug delivery patch and corresponding heating element that can facilitate treatment of breakthrough pain, and/or that can be regulated to match the body""s circadian rhythms, and/or that can provide additional booster drugs when necessary.
It is another object of at least one embodiment of the present invention to provide an electrical heating element advantageously and removably secured to a transdermal drug delivery patch.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims.
To achieve the foregoing objects, and in accordance with the invention as embodied and broadly described herein, the present invention comprises a securable, heating element compartment with a corresponding, freely-transferrable heating element. The heating element compartment may be integrated with or secured to a transdermal drug delivery patch (drug patch). The heating element compartment provides an area of restraint that prevents the freely transferrable heating element from being displaced relative to the drug patch to which the heating element compartment is secured.
The freely transferrable heating element limits the likelihood that a drug patch will become dislodged or displaced during the placement, transfer, or replacement of the heating element. Thus, the freely transferrable heating element is secured proximate to a drug patch but, nevertheless, is easily removed and replaced with use in conjunction with the heating element compartment of the present invention. The heating element does not require an adhesive to be secured to the drug patch, nor does it need to be wrapped or otherwise tied to the patch or patient.
The heating element can be secured or retained in the area of restraint within the heating element compartment using the novel techniques disclosed herein, or alternatively, techniques known in the art. Novel techniques for restraining the freely transferrable heating element include using the top of the heating element compartment to provide tension and downward pressure upon a heating element within the heating element compartment. Tension or downward pressure may be provided by sealing at least one edge (or a portion of an edge) of the top of the heating element compartment to create an area of restraint within the compartment disposing a corresponding heating element within the heating element compartment. Because the heating element corresponds to the pouch either in relative shape or size (being approximately the same size and/or shape), the heating element fits snugly into the compartment and is secured within the heating element compartment in an area of restraint. The edge of the heating element compartment may be sealed and secured to a drug patch or may be sealed and secured to a bottom portion of the heating element compartment. The top may be integrated with the patch or may be secured to the patch or releasably secured to the patch.
The heating element compartment also provides a physical barrier limiting relative displacement of the heating element. In one embodiment, the heating element is contained within the compartment by sealing and securing at least a portion of an edge of the top. The sealed edge contains the heating element within the compartment and prevents the compartment from being unintentionally displaced out of the compartment.
Another potential means of restraint is the use of materials that have or create sufficient frictional forces between the heating element and the heating element compartment to resist the displacement and restrain the heating element in the compartment when the heating element experiences a directional force that would otherwise displace the heating element. Similarly, a clip or slide mechanism may be provided to restrain the heating element as shown in FIGS. 15 and 16. Limited adhesion or a very light weight adhesive within the heating element compartment may also provide a force, for resisting lateral displacement of the heating element.
The heating element compartment comprises at least a top for defining the compartment and at least a portion of an edge of the top that is secured. The edge may be secured to a transdermal drug delivery patch (drug patch). Alternatively, the edge may be secured to a bottom of the heating element compartment. If the top is secured to the drug patch, the top side of the drug patch may serve as a xe2x80x9cbottomxe2x80x9d for the heating element compartment; the top is secured at least along one edge (or a portion of one edge) to the transdermal drug patch. The top and bottom or the top and the drug patch define a heating element compartment that is secured, or is capable of being secured to or is integrated with a transdermal drug patch. Thus, the top is secured to the patch or alternatively, the top is secured to a bottom to form a pouch.
The top may have a shape that corresponds to the shape and size of the heating element to facilitate the restraint of the heating element in the restraining area of the heating element compartment. As shown in FIGS. 1 through 20, the top may be any number of shapes and sizes. The shape of the top (as well as the heating element) may be oval, circular or semicircular, polygonal, or any other number of shapes. At least one edge or a portion of one edge of the top must be sealed to the drug patch, or in the alternative, to a bottom sheet to form a heating element compartment or a pouch.
The top may be manufactured from any number of materials known in the art. The qualities of the material may affect the design of the pouch and the corresponding heating elements, and may affect or even dictate the type of treatment with which the pouch and heating element can be used. The top may be air permeable, air impermeable, or selectively permeable. It may be translucent, transparent, or be a particular color. The top may have inherent insulative properties or may be designed and manufactured to have enhanced insulative properties. The top and/or the compartment defined by the top may also protect and shield the heating element once the heating element is in place. The top may be rigid, but is preferably flexible and elastic.
Some of the embodiments of the present invention require that oxygen or air be able to pass into the heating element compartment, others do not. If the heating element does not require air to pass through into the heating element compartment in order to function, the top of the compartment can be made of a material which is air impermeable. Thus, the materials used to form the heating element compartment will depend in part upon the type of heating element selected. Characteristics of the pouch""s construction may vary depending upon the use of the pouch, but the pouch should be securable or integrated with the heating patch and should allow the heating element or the pouch contents to be freely transferred into or out of the pouch at a desired time.
In one embodiment, the heat from the heating element activates adhesive on a portion of the top, such as the entry space into the pouch, and seals the pouch when that portion is closed. When the heating element stops generating heat, the adhesive is deactivated and the pouch opens or is more readily opened along that portion.
The freely transferrable heating element of the present invention is a device capable of delivering controlled heat to the transdermal drug delivery patch and/or the patient""s skin The heating element is of a size and shape that corresponds to the securable heating element compartment. The freely transferrable heating element can be placed in the heating element compartment and remains secured in the area of restraint relative to the drug patch. The heating element compartment reduces the likelihood that the freely transferable heating element will be unintentionally dislodged until the heating element is intentionally removed from the compartment and drug patch. The heat from the heating element can be generated using a chemical reaction, such as an oxidation reaction, electrical heat, or other means of generating controlled thermal heat. Other methods for generating heat, such as crystallization, microwave, or infrared heat, are also contemplated.
The heating element may provide insulation to the drug patch and skin, and may be designed to provide additional insulation to maintain a higher, controlled temperature. The heating element shapes and sizes may correspond to the shape and sizes of the heating element compartment and have substantially similar dimensions. The heating element is designed to allow the heating element to be placed within the heating element compartment with relative ease and to be removed from the compartment with relative ease, but nonetheless remains secured in the compartment to reduce the likelihood the heating element will be unintentionally displaced from the compartment or separated from the patch.
The heating element of the present invention can provide heat for a particular duration. Where the heating element is an electrical heating element the duration of the heat may be any amount of time limited only by the ability of the battery or electric power supply to supply current to the electrical heating element. The electrical heating element can pulse on and off as necessary and the replacement drug patches can be supplied as frequently as necessary. Heating elements that use chemical reactions can be designed, manufactured to provide heat for a given duration.
The heating element provides controlled heating. Controlled heating allows the user to provide a level of heat that results in an increase in temperature to a predetermined or prescribed range. Controlled heating is preferable to heating devices that are not controlled. If the heating element is incapable of delivering controlled heat, it becomes difficult to regulate the amount of drug being delivered, and the potential for overdose or underdose is significantly increased. Similarly, the patient""s skin may be blistered or burned by uncontrolled heat. By being secured in the area of restraint within the compartment attached to the patch, the heating element provides uniform, controlled heating.
One embodiment of the heating element comprises a chamber defined by air impermeable walls. The chamber is defined by a bottom wall, a top wall and side walls. The heating element preferably comprises the composition of activated carbon, iron powder, sodium chloride, water, and optionally, sawdust, which is disposed in the chamber. The top wall is preferably a flexible air impermeable material having a plurality of holes therethrough. The top wall may be an air permeable membrane or an air impermeable material with a plurality of holes. The top wall can have at least one covering for the plurality of holes or can have a covering to prevent air from passing through the air permeable membrane. In the embodiment having a plurality of holes in the top wall, the holes can be selectively covered and uncovered. By selectively covering and uncovering the holes in the top wall, the heat and duration may be varied and administered as desired.
The present invention can be used to increase the serum concentration of the drug delivered by the drug patch by a desired amount. For example, it may be necessary in treating a particular patient to increase the serum concentration of the drug delivered by the drug patch by 10% over the normal serum concentration as established by the drug patch""s steady state. The present invention allows a controlled increase in temperature, which can be maintained at the increased level and if desired, returned to the original steady state level without changing the drug patch used to deliver the drug. Similarly the patient may find that an increase of a certain percentage is necessary for certain activities. A patient may need an increase in a drug serum concentration level during a period of increased physical activity or may require less drug during a period of rest. The present invention provides the capacity to conveniently adjust drug serum concentration levels by applying controlled heat and does so in a way that limits the chances that the drug patch will be dislodged or compromised during the application.
The securable heating element compartment can be integrated with a specially designed drug patch, or used in conjunction with drug patches known in the art. Where the drug patch is integrated with the heating element compartment, it may be advantageous to only use a top to form the securable compartment. Where the patch is a pre-existing patch or one available in the market, the top sheet may need to be combined with a bottom sheet to form a securable heating element compartment. The securable heating element compartment should be of a shape and size to correspond to the specific drug patch.
The heating element should be of a shape and size to conform or correspond to the heating element compartment and the heating element should be designed for safe and effective use with a particular type of drug patch. For example, the freely transferable heating elements designed for use with transdermal fentanyl may have a particular size and shape and color. For a patch with a different drug, such as a testosterone patch, the colors and shapes of the heating element may be different than those for fentanyl. Thus, it is preferable that the shapes and sizes of the securable heating element compartments, and in particular the heating elements, be designed and manufactured so that the compartments and heating elements designed for use with one type of drug patch are not readily useable or interchangeable with another type of drug patch. The color may indicate the type of drug with which the securable compartment and heating element should be used and may also indicate the desired effect the compartment and heating element are intended to have. If a securable compartment and heating element is designed for a particular drug patch and if use of the heating element with a different drug patch could cause harm or overdose, the heating element and corresponding compartment should be designed so as not to be compatible with the drug patches that could result in such harm.
The present invention allows for heating elements and other articles to be placed proximate to a transdermal drug patch using a heating element compartment or pouch. For example, the compartment or pouch could be used to retain various devices which could be advantageously placed proximate to the drug delivery patch, such as iontophoresis devices, timing devices, notification or reminder devices, any type of heating and/or cooling mechanisms, patient or patch monitoring devices, alarms, timers, watches, microprocessors, thermostats, thermometers, use indicators, and potentially and various novelty items such as toys for encouraging the use of the delivery system by children.
It is understood that a considerable variety of drug classes and specific drugs can be used with the present invention. Drug classes may include without limitation androgens, estrogens, nonsteroidal anti-inflammatory agents, antihypertensive agents, analgesic agents, antidepressants, antibiotics, anticancer agents, local anesthetics, antiemetics, antiinfectants, contraceptives, antidiabetic agents, steroids, anti-allergy agents, anti-migraine agents, agents for smoking cessation, and anti-obesity agents. Specific drugs include without limitation nicotine, testosterone, estradiol, nitroglycerine, clomidine, dexamethasone, wintergreen oil, tetracaine, lidocaine, fentanyl, sufentanil, progesterone, insulin, vitamin A, vitamin C, vitamin E, prilocaine, bupivacaine, sumatriptan, dihydroergotamine, and scopolamine.